Analysis of Power Fluctuation at DC Side Caused by Unbalanced AC Voltage of Hybrid Microgrid and Relative Solving Measures

In the hybrid AC/DC microgrid, the unbalanced voltage at DC side will lead to the fluctuations of DC voltage and power. In this paper, the characteristic of the DC voltage and power fluctuations when unbalanced fault occurs at AC side is analyzed, and the composition of DC component, frequency component and the double-frequency component contained in the DC voltage and power under such cases as the accessing of DC capacitor and resistor to DC side and DC micro-grid is studied. Then a measure to eliminate the voltage and power frequency component is presented by accessing of single-tuned filters at the DC side. In the end, the PSCAD/EMTDC simulation results show that large frequency component is contained in DC voltage and power and the single-tuned filters can handle this problem effectively.